Spark plug



H. EARLE SPARK PLUG Filed July 19. 1920 7 I Patentetlflt v of i Ui it tesaresidingatWa V the tllln' -co.ndu ti g i g is riTo -all it-hem t ma QM M 5 H mymemjorwammmassaenesmmsg1: i

Application ma Jiu ie,

Be itknown thatI, HEN YLEA LnQa citi'-;

"'rernin the county of Worcester and State of Massachusetts;have invented certainnew V r c and. useful Improyementsan; Spark Plugs,

' of which'the following "ls'a'fspeoification,

I g My invention relates to sparkrplugssnch.

as are used ingas engines for ignition of the exglosiye mixture.

'These spark phig 'freqnently becoine coy;

V V ered with 7 carbon and the accumulation of carbon between the two electrodes frequent- 'ly results gin short T cireiiits which I greatly reclucethe efliciency ofthesparkplug; V H The object of my inyention' is to insulate '7 as completely as possible, the surface ofthe central electrodeor other metallic parts of a spark plug, so that no currentor ignition spark can pass except between two'small unprotected spots. rI' harveffoiindit sufficie'ntfor the purpose toc'o-atthe central electrode of alspark plug with adiflicuitly reducihleymetallic oxide, preferably of the iron and chromium groups 'of-metals; i For instance, thesurface of the;- centralityire electrode of a spark plug-isfc'oateclwith an oxide. of uranium that is notrednciblefin A the gases "formed 'inj'a ni internal combustion I no engine,-an'cl is for all practical'pnrposesnom Y conclncting; Also, I have"fouinlthatfif; a metallic surface isco ated;.with 1 a metallic 1 ing it to a'cherry red;

' phosphate or phosphi'de,'itisrendered prac tically nonconoluctirig. For thispurpose, I

dip the nlet-a1 to be coated in a solnticm of phosphoric acid anclthen applyheat, heat The phosphate'first-gforinecl" the r face is-converted by thehigh temperature I .40 1 temperature into a phosphide which-is highly'non-conducting; jA'fter'a sparkplug'elec trod e iscoInpletely c0ated, I remove the;

Coating that it will an uninsulatecl spot just-oppositejthe. dis-1;

into a ineta'phosphate and at a still higher coating -with a sharp instrument 51:0; formf charge point of theothereiectrode; so that.

no e current-can pass. except where; the spot 7 'is' fonned 'andlthe coatingiis removed. I The Y wrest of thesparlrplnggbeing completely insnlated, there can he no leakage; of current by a coating oficarloon *or'sootj-forming on -;fthe inside of the plug or p11 .the 'e'leetrode- 1 'surface, is intensely hot,;1 nuch inore so than: {if the'nnprotectedsurface was larger and there being no leakage'of currentthrough the sicleof thewire 1. Q The insulating coating of metallic oxide or other, insulating materialisgappliecl to I n the surface of th'efelectrode wirel by. dip} i ,i; 7 'ping the wir'econe or more times; into a so-:" vj' i lution then heating the wire to" a l w T red heat. I

:circnit being formed. I

A spark plngmade on thisprincipal-costs r ordinary spark 7 V. a

526: Sa r-m.- 397, 31;

l ee et"e n r sobt'githe fail-Q h c rentisaanzea,

; Althoughthefvoltage on these spark sufficient to. rresi'stthe penetration "by any i chargesiwhioh might passin ashortl'cireuit since the feleetrieity will always pass over the line of least re uninsulated fsp ot sistanceorthroughfthe Y f? 1 1. 7} r evident that 'thenon-conducting coatin}; may be an adherent eoatingias shown. or

it .Iha-y he a thin covering of insulating I g Referring :to the drawing 1; shows the; main oncentral wire electrode i A} spot l is thenfs crape ql a 'suitahle i051 of 'a/spark gav di 2: is theterm'inal wire-915, ofgthe 'annularelectrode"3, the spark heing formed between the end ofth'e wire Qand t: .z r

s; V *lfronrthe sicle ofthe wire 1 directly opposite togtheencl of the Wirev 2- fria't the point where;

thespa'rk jumps across.

is'effectively insulated except the one small buta trifle more than the: plug and ahsolutely iprevents short circuiting by thebarbon formedjwithin the' oombastion chamber, 'a-sourceQo-f much trouble in the:present gas engine practice. 1 for my non-conducting Q 10o but only" Ijdo not claim insulate against a high tension intermittent s eurrent 1 against adirectcurrent; i v

i :The entire efiectivelength of the wire! :00 Y spot so'that thereis no chance of any short" c I is evident that whefejthe tension on the icoa tingbecomes snificient to perforate'the j I A r game the coating willhepnnotured a-t-some spot by the sparkandl the subsequent effect will bethesamea sfi ffl formegl the 's'potlin f1 )7 '7 7 manufacturing the electrode. .As high ten-j sion alternatingfcnrrents are mostly used on gas ,engines,: there is no rea lf n'eces sity of V scraping 'ofl'rthe coating to jfornafthe bas'ef f spot: 7

lief

i I I dam};

l.-A: spark plug t iwo electrodes,

' o'neoffthe said electrodes having an adherent coating of I non-conducting material extending over substantially all. its effective surface, a POICIOIL Of szud, non-conductmg: nmterlalv .bemg removedirom spot opposite the other electrode." a [2. Ar sqga'rlnplu'gv ha'vingfltwo electrodes,

one of said electrodes being coated vi th aw cozrtingof metalliof'phosphate, thesaidl coat-1 d ng-being removed fro other electrode. Y I V V w 1 1 '23. A: sper'k phigfhaving, txvofelectrodes,

,a spoti'opposite the one of said' electrodes having been dipped in a solution ofrphosphoric acid. and subsequentlyheated to 7 form] a non-conduomng coating, said coatingbeing removed from av spot opposite the other electrode.

4. A sparkplugheving'two electrodes, one of said e1e-ctrodes ha-ving a coating of metallicr'phosphate overlaid with a coating of uranium oxide; a portion of said double coating being removed at" a spot opposite the other elec'trode.-.-

o ln testirnony Whereof'I afiixmy'signzrture. V 

